/* Copyright (c) Huawei Technologies Co., Ltd. 2023-2024. All rights reserved.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
 ==============================================================================*/

#ifndef MXREC_LIMITED_SET_H
#define MXREC_LIMITED_SET_H

#include <cstdint>
#include <vector>

namespace EmbCache {

class LimitedSet {
public:
    struct Node {
        uint64_t value;
        Node *prev, *next;
        explicit Node(uint64_t val = NODE_DEFAULT_VALUE) : value(val), prev(nullptr), next(nullptr) {}
    };

    explicit LimitedSet(uint64_t maxRange) : head(new Node(NODE_DEFAULT_VALUE)), tail(new Node(NODE_DEFAULT_VALUE))
    {
        nodes.resize(maxRange);
        for (auto &node : nodes) {
            node = new Node(NODE_DEFAULT_VALUE);
        }
        head->next = tail;
        tail->prev = head;
    }

    ~LimitedSet()
    {
        for (auto &node : nodes) {
            if (node != nullptr) {
                delete node;
            }
        }
        if (head != nullptr) {
            delete head;
            head = nullptr;
        }
        if (tail != nullptr) {
            delete tail;
            tail = nullptr;
        }
    }

    LimitedSet(const LimitedSet& other): head(new Node(NODE_DEFAULT_VALUE)), tail(new Node(NODE_DEFAULT_VALUE))
    {
        nodes.resize(other.nodes.size());
        for (auto& node: nodes) {
            node = new Node(NODE_DEFAULT_VALUE);
        }

        head->next = tail;
        tail->prev = head;

        for (Node* node = other.head->next; node != other.tail; node = node->next) {
            insert(node->value);
        }
    }

    LimitedSet& operator=(const LimitedSet& other)
    {
        if (this == &other) {
            return *this;
        }

        if (head != nullptr) {
            delete head;
            head = nullptr;
        }
        if (tail != nullptr) {
            delete tail;
            tail = nullptr;
        }
        for (auto &node : nodes) {
            if (node != nullptr) {
                delete node;
            }
        }

        nodes.clear();

        LimitedSet temp(other);

        std::swap(head, temp.head);
        std::swap(tail, temp.tail);
        std::swap(nodes, temp.nodes);

        return *this;
    }

    void insert(uint64_t value)
    {
        if (nodes[value]->value == value) {
            return;
        }
        Node *node = nodes[value];
        node->value = value;
        Node *next = head->next;
        node->next = next;
        node->prev = head;
        head->next = node;
        next->prev = node;
    }

    void remove(uint64_t value)
    {
        if (nodes[value]->value != value) {
            return;
        }
        Node *node = nodes[value];
        node->prev->next = node->next;
        node->next->prev = node->prev;
        node->value = NODE_DEFAULT_VALUE;
    }

    bool find(uint64_t value)
    {
        return nodes[value]->value == value;
    }

    class Iterator {
    public:
        explicit Iterator(Node *node) : current(node) {}
        bool operator != (const Iterator &other) const
        {
            return current != other.current;
        }
        const uint64_t &operator*() const
        {
            return current->value;
        }
        Iterator &operator ++ ()
        {
            current = current->next;
            return *this;
        }

    private:
        Node *current;
    };

    Iterator begin() const
    {
        return Iterator(head->next);
    }

    Iterator end() const
    {
        return Iterator(tail);
    }

private:
    Node *head;
    Node *tail;
    std::vector<Node *> nodes;
    static constexpr int64_t NODE_DEFAULT_VALUE = -1;
};

}
#endif // MXREC_LIMITED_SET_H
